Variable resistor indicating and locking device



Sept. 24, 1968 w D ETAL 3,402,693

VARIABLE RESISTOR INDICATING AND LOCKING DEVICE Filed April '7, 1966 2 Sheets-Sheet 1 INVENTOES DONALD 6. 774/550, A JOHN R L/UNGBLUT Sept. 24, 1968 TwEED ETAL 3,402,693

VARIABLE RESISTOR INDICATING AND LOCKING DEVICE 2 Sheets-Sheet 2 Filed April '7, 1966 INVENTOES DONALD 6. 771/550, JOHN R L/UNGBLUT United States Patent Office Patented Sept. 24, 1968 3,402,693 VARIABLE RESISTOR INDICATING AND LOCKING DEVICE Donald G. Tweed and John R. Jungblut, Riverside, Calif., assignors to Bourns, Inc. Filed Apr. 7, 1966, Ser. No. 540,985 6 Claims. (Cl. 116115) ABSTRACT OF THE DISCLOSURE A variable resistor indicating and locking device for a multi-turn variable resistor or potentiometer, having fixed means including a base adapted to repose against a face of a panel and a rotary member to receive and be affixed to a rotary shaft of the resistor, the rotary member being rotated by gearing connected to a manually rotatable shell, and the fixed means supporting a digital counter connected to be driven by the gearing, and the fixed means having a contractile locking band and a lever operable to permit the band to clasp and lock the rotary member and opera-ble to force the band out of engagement with the movable member to permit manual rotation of the shell and gearing to adjust the resistor.

The invention herein disclosed pertains to potentiometers, and more particularly to potentiometers of the socalled multiturn type in which adjustment of the instrument through its entire range of adjustment is effected by rotation of a shaft or like instrumentality through a plurality of turns or revolutions. Still more specifically the invention pertains to means connected to the adjustment shaft for selectively rotating the shaft for efiecting adjustment and providing a visible numerical indication of the extent of the adjustment, and for locking the shaft against rotation While retaining the indication of the eX- tent to which adjustment has been effected.

Many devices have been developed with a view toward performing some or all of the aforedescribed operational functions, among which devices may be cited those disclosed in the following numbered US. patents, viz: Van Dyke, 2,532,970; George, 2,539,575; Van Dyke, 2,558,- 326; Coates, 2,658,395; Van Alen, 2,979,258; Arnold et al., 3,136,294; Tofita, 3,031,035; and Ihrig, 3,172,071. All such devices known to the present inventors have been characterized by one or more undesirable features, such as, for example, high cost, complex structures, difiiculty of assembling, low operating lifetime, indication of extent of rotation presented on one or more scales which are difficult to read, and cumbersome structure presenting unsightly appearance. The present invention, by a unique combination, avoids the aforementioned undesirable features or characteristics of the noted prior art devices, and presents a simple, inexpensive and very effective structure which in meritorious fashion performs all of the aforenoted functions.

Briefly, according to the invention, there are provided rotary means including a transmitter adapted to be secured to the rotary adjustment shaft of a multiturn potentiometer or the like, which rotary means is arranged to support and retain against the panel through which the shaft extends, certain relatively stationary structure including support means which serves to support indicating means and which stationary structure is prevented from partaking of rotary movements in a convenient manner, as by being keyed to the panel. Further, the stationary structure rotata'bly supports a captive rotary shell which is arranged for manual manipulation in the manner a knob would be manipulated, the captive rotary shell being connected by gearing to the indicating means to operate the latter, and being further connected by the gearing to the aforenoted rotary means, whereby incident to rotation of the shell the rotary means and the shaft are simultaneously rotated and concurrently the indicating means are rotated to furnish an indication of the currently effective extent of rotation of the shaft from an initial or zero position. Further according to the invention the stationary struc ture supports and holds against rotation a contractile spring device which normally is contracted and grips and locks against rotation the transmitter 'by its inherent tension but which spring device may be expanded by a key means which has a spreader which when rotated to a first attitude acts against the tension of the spring device to spread or expand the latter and release the locking grip of the spring device on the transmitter, and when moved to a second attitude or position releases the spring which then locks the transmitter against accidental or other unintentional rotation. Preferably, one or the other of the contractile spring device and the rotary device is equipped with friction means whereby the grip of the contractile device on the rotary means and the locking action thereof is enhanced; and that is most efficaciously accomplished by provision of an elastic preferably rubber-like or elastomer band disposed under tension on a flange or skirt of the transmitter in a position to be engaged and gripped by the contractile spring device. The contractile device may conveniently be a C-shaped band anchored at its middle to the stationary structure, or, alternatively, may be a coil spring having closely-adjacent ends arranged to be spread by the spreader and a diametrically-opposite formation engaged by the stationary structure to anchor the spring device against rotation.

By virtue of the thus generally described arrangement, the means according to the invention provides an easilyread digital indicating apparatus visible at an end of a knob-like manually operable rotary shell which blends simply and in attractive arrangement with the stationary structure, and which indicating apparatus is housed Within and protected by the shell and operated thereby concurrently With operation of the rotary shaft-rotating means, the entire apparatus and means, including the locking means, being adapted for easy and rapid placement on or removal from the shaft of a potentiometer. Further, the locking device, being a resilient contractile member effective to lock the rotary means when released, does not permit of an operator exerting an excessive force thereon incident to operation of the lock, and thereby eliminates the possibility of lock-breakage and/or insufiicient locking, as are both usual in the prior art devices.

The foregoing brief general description of the invention makes it evident that it is a principal object of the invention to provide improvements in means for alternatively and intermittently rotating and locking the shaft of a multiturn potentiometer while concurrently providing a digital indication of the extent of rotation of the Shaft.

Another object of the invention is to provide general improvements in means for operating upon the shaft of shaft-adjusted potentiometers and providing indications of the extents of adjustments.

Another object of the invention is to provide improvements in shaft-locking devices for manually operable shaftadjusted variable resistors.

Other objects and advantages of the invention will hereinafter be stated or made apparent in the following detailed description of a presently-preferred exemplary embodiment of the invention, in which description references are made to the accompanying drawings forming a part of this specification and in which drawings:

FIGURE 1 is a pictorial view, to no particular scale, of the noted exemplary embodiment of the invention;

FIGURE 2 is a face view of the device illustrated in I 3 FIGURE 1, with a portion broken away to reveal internal details;

FIGURE 3 is a sectional view of the structure depicted in FIGURES 1 and 2, thesection being taken as indicated by broken line and arrows 3--3 in FIGURE 2, but on a different and larger scale; v

FIGURE 4 is a sectional view of the structure depicted in FIGURES 1 and 2, the section being taken as indicated by broken line and arrows 44 in FIGURE 2, but on a different and larger scale;

FIGURE 5 is a rear view of the device as viewed on a plane indicated at 5-5 in FIGURE 4, to approximately the same scale as that of FIGURE 1;

FIGURE 6 is a view similar to FIGURE 5, to a larger scale and with a part removed to show internal details;

FIGURE 7 is a view similar to FIGURE 6, but showing a modified form of resilient contractile locking member;

FIGURE 8 is a front view of the device, with certain parts removed to illustrate internal details;

FIGURE 9 is a pictorial view of members of the locking structure in disassembled relationship;

FIGURE 10 is a pictorial view of a support, depicting details of the rear end thereof;

FIGURE 11 is a face view of a base device forming part of relatively stationary stnucture comprised in the device, to no particular scale;

FIGURE 12 is a pictorial view of a retainer ring or washer;

FIGURE 13 is a front view of the support, showing details of construction; and

FIGURE 14 is a rear view of a cap element which is adapted to be secured to the front of the support depicted in FIGURES 10 and 13.

Referring first to FIGURE 1, the assembly of components comprised in the preferred embodiment, and hereinafter termed the assembly, is denoted generally by numeral 10. The assembly includes a ring-like base 12 the fiat rear face 12 (FIGURE 4) of which is adapted to seat against the front face of a panel P through which an actuating shaft S of the variable resistor Q extends. The variable resistor may be, by way of example, a rnultiturn potentiometer of the character of that disclosed in US. patent to Blanco, No. 3,156,888. The variable resistor comprises a threaded bushing, B, and a nut, N, by means of which it is adapted to be secured in place on the panel in a known fashion. Fitted in an annular stepped recess (12x, 12y, 12z, FIGURE 11) formed at the front of base 12, and held in place therein as by being ad hesively secured therein, is a support 14 (FIGURES 10 and 13) of hollow cylindrical shell-like form having a complex end and interior configuration. The functions of the support are several, as will presently be made evident. Arranged between base 12 and support 14, and held clamped therebetween as indicated in FIGURES 3 and 4, is a retainer ring or washer 13 (see also FIGURE 12) and one or more annular shims 12', whose functions will later herein be explained.

Rotatably disposed on the cylindrical exterior of support 14 is an elongate cylindrical shell 16 (FIGURES l, 3 and 4) the skirt of which extends back into close proximity to a flat annular front face 12a of base 12. Shell 16 |has a radially inwardly-extending annular internal flange 16f (FIGURE 4) the rear face of which carries a ring (gear 16g and an annular portion of which bears against a complementary annular front face of support 14. Further, shell 16 is held captive in that attitude on support 14 by a fenestrated cap 18 (see also FIGURE 14) of generally circular outline and the rim portion of which is disposed in front of annular flange 16 and which cap is secured to the front end of support 14 as by adhesive applied on the complementary contacting surfaces. A transparent pane or disc 20 is fitted in a bezel formed in the front end of rotatable shell 16, whereby the interior of the assembly is effectively sealed against ingress of foreign matter.

Disposed in elongated aligned coaxial semicylindrical seats 14s and 14s (FIGURE 13), provided at the front face of support 14, are respective ends of a counter-pinion shaft 22 (FIGURES 2, 4 and 8) upon which are rotatably supported for independent rotation first and second counter pinions 24 and 26 as shown in FIGURE 8 The shaft 22 is held from escape and retained in place by a rearwardlyextending complementary pedestal 18p (FIGURESA and 14) provided on the rear face of cap 18; and pinions 24 and 26 are accommodated in a complementary notch 14m formed between the seats in support 14 as indicated in FIGURES 8 and 13. Pinions 24 and 26 are of the type commonly employed in counting mechanisms, and have one-half of the length of alternate teeth cut away or missmg.

Rotatably disposed in respective saddles 14:1 and 14r formed in forwardly extending struts such as 14p (FIG- URES 3 and 13) formed as integral portions of support 14 are one end of a counter wheel shaft 28 (FIGURES 3 and 4) and the hub 30h of a first counter wheel 30 which is fixed to the shaft 28 to turn therewith. Loosely disposed on shaft 28 next-adjacent each other as shown are second and third counter wheels 32 and 34. The counter Wheels are of the type commonly used in decimal (tens) counters or revolution counters. Further, afiixed to an extending end of shaft 28 is a pinion 36 (FIGURE 3) the teeth of which are engaged with the teeth of the previously mentioned rearwardly-facing internal ring gear 16g. The latter gear is preferably formed as an integral part of rotary shell 16. Thus pinion 36 and wheel 30 are rotated incident to rotation of shell 16, and, through operation of pinion 24 by the gear of wheel 30, the operation of wheel 32 by pinion 24, etc. (in the manner of conventional counters), the counter is driven to provide a direct numerical indication of the extent of rotation of shell 16.

Rotatably supported in an accommodating recess 14k formed in member 14 (FIGURE 13), and rearwardly of pinion 36, is an idler pinion 38 (FIGURE 3) which is rotatable on a stationary pin 40 affixed at its ends in support 14. Idler pinion 38 is in mesh with teeth of a forwardly-facing ring gear 42g which preferably is formed integrally as a molded part of a rotary transmitter 42. Rotary transmitter 42 is adapted to be locked to the shaft S of the potentiometer, as by set screw means 42s as indicated in FIGURE 4. Access to the set screw means is via apertures or notches such as 14x, 14y (FIGURE 10) provided in the skirt of support 14, and via similar notches provided at the rear end of shell 16 as indicated in FIG- URE 1. Thus it is evident that when shell 16 is rotated, the teeth of gear 16g thereon rotate the counter-driving pinion 36, the latter rotates idler pinion 38, and pinion 38 in turn rotates transmitter 42 to cause concurrent rotation of shaft S of the potentiometer. Transmitter 42 is held captive in the interior of support 14 by the aforementioned retainer ring 13 (FIGURE 12), which is clamped between base 12 and support 14 as indicated in FIGURES 3 and 4. As indicated in FIGURES 10, 11 and 12, the retainer ring 13 has radial extensions 13x, 13y which fit in complementary sectors of the steps 12x, 12y formed in the bottom of the annular stepped-recess 12z formed in the forward part of base 12. Also, complementary rear extensions 14w and 141 (FIGURE 10) provided on support 14 are arranged to fit into the sectors or recesses 12x and 12y and clamp therein the radial extensions 13x and 13y of retainer ring 13. Thus when support 14 and base 12 are adhesively united or secured together the transmitter 42 is confined in the interior of support 14, and the teeth of gear 42g are in contact with and are driven by pinion 38. If the gear ratios are 1 to 1 between ring gears 16g and 42g, as shown, the shaft is rotated one revolution per revolution of shell 16. If necessary, one or more shims 13s may be used with retainer ring 13 as indicated in FIGURE 3.

The transmitter 42 is the means whereby the base, the support, the shell, and other parts are held in together as a united assembly; and in position at the front of a panel P. Since the transmitter 42 is captive, the entire assembly as a unit is attached in position by tightening the set screw means 42s, or is released by loosening the set screws. The base 12 is restrained from rotating around the axis of shaft S as the latter is rotated, by a specially formed antirotation member 44 (FIGURES 3, 4 and 5) which is clamped between the panel and bushing nut N and which has a rearwardly-extending key 44k arranged to repose in a small hole bored in the panel as indicated in FIGURE 4. Member 44 thus is prevented from rotating around the bushing, and in turn is effective to prevent rotation of base 12 by the action of radially extending arcuate keys 44a, 44b (FIGURE 5) which fit snugly in complementary shallow arcuate recesses 12b, 120 (FIGURE 6) formed at the rear face of base 12. Thus the angular disposition of the locking indicator device or assembly relative to panel P is determined by the position of the small hole in panel P, into which key 44k fits. With antirotation member 44 secured in place against the front face of panel P, the locking indicator assembly is applied to the protruding end of shaft S and rotated and moved rearwardly on the shaft until arcuate keys 44a and 44b are seated in recesses 12a and 12b. Thereafter but with the potentiometer shaft S previously driven to its lower extreme of rotation and with the counter wheels registering zero, the transmitter set screw means 42s are tightened to thereby positively interconnect the shell 16', the indicator and shaft S into a positively articulated chain or series of components, and to positively attach the locking indicator assembly in position on shaft S in front of panel P. It is desirable to exclude foreign material from the interior of the counter mechanism prior to application of the assembly onto shaft S, and for that purpose a thin disc, 42d (FIGURE 4) is fitted in a shallow recess provided in the front face of the transmitter 42, encircled by ring gear 42g.

The connection of the indicator wheels 30, 32 and 34 to shell 16 via gears 16g and 36 and the associated pinions is such as to provide by wheels 30, 32 and 34 a digital indication, by tenths of a revolution, of the extent of rotation of shell 16 and shaft S. For example, when the indicator is for use with a so-called ten-turn potentiometer, gear 16g may have seventy teeth, pinion 36 seven teeth, wheel 30 two teeth, pinions 24 and 26 each four alternate full teeth and four intervening half teeth, wheel 32 twenty teeth in engagement with the full teeth of pinion 24 and wheel 32 having two teeth to engage the four full teeth of pinion 26, and wheel 34 having twenty-two teeth to be driven by the eight teeth of pinion 26. The numbers of teeth and arrangements thereof in the gearing are susceptible of variation to allow accommodation of the locking indicator structure to potentiometers of, for example, twenty turns, thirty turns, five turns, etc., in accord with well-known gearing design principles as used in conventional turns counting mechanisms.

To permit concurrent locking of both the shaft and indicator means there are provided novel lock means adjacent the panel at the rear end of the structure, utilizing ordinarily wasted space encircling the bushing nut, and out of the way of the operator when adjusting the instrument. For that purpose, and as depicted at the top of FIG- URES 4 and 6, there is disposed in a forwardly-extending notch 12x formed in the top portion of base 12 the stem 46s of a rotatable key 46 which is held from escape from the notch by circumferential flanges provided on the stem of the key as indicated in FIGURE 9, and by the panel P. The lower end of key 46 is formed as a flat blade 46b (FIGURES 4, 6 and 9), which blade is positioned and disposed between the operating tips 48a and 48b of a resilient strongly contractile spring lock 48 as shown in FIGURE 6. In the preferred form, lock 48 is a spring band shaped to provide first and second contractile arcuate drum-engaging limbs 48c and 48d which when permitted to do so are effective to grip between them opposite por- 6 tions of a rearwardly-extending cylindrical portion or drum 42d formed integral with transmitter 42 (FIGURES 4 and 6). Preferably the drum is provided with an adherent or attached friction facing 50. Thus when the drum is gripped between the limbs of the lock 48, the transmitter 42 and shaft S are locked against rotation. In a preferred form the friction facing 50 is in the form of a tensioned tough elastomer band which in the relaxed state is of diameter somewhat less than the outside diameter of drum 42d. Thus facing 50 may be secured to the drum 42d by its own contractive effort following elastic expansion and fitting on the drum. Lock 48 is restrained against rotation with drum 42d by an anchor 12a (FIGURES 4 and 6) which is formed as a rearwardly-extending pin-like protrusion integral with and a part of base 12, the lock having a restricted sharply-curved bight portion 48a which engages the anchor as shown.

Lock 48 is constructed of strong resilient material such as spring steel, and is formed to produce a locking grip on drum 42d when allowed to contract as shown in FIGURE 6. Thus it is formed so that it must be expanded or have limbs 48c and 48d spread apart before receiving drum 42d and facing 50. A complementary groove 12y is provided in base 12 around anchor 12a for reception of the bight 48a of lock 48, as is made evident in FIGURE 6, the groove being dimensioned to accommodate expansion and contraction of the lock. The limbs of lock 48 are adapted to be expanded or spread out of locking engagement with facing 50, by spreading force applied to tips 48a and 48b by the blade 46b of key 46 as the latter is rotated. Thus as the key is rotated the blade 46b, being longer (FIGURES 4 and 9) than the gap between tips 48a and 48b, acts as a pair of cams and spreads the tips and limbs of the lock. Since in the expanded attitude of the lock the lips thereof exert a strong frictional grip on the ends of the blade of the key, the latter is effective to maintain the lock in the released attitude until it is manually turned to the position indicated in FIGURE 6 in which the lock again is effective to lock transmitter 42, shaft S, shell 16, and the indicating means in their then-current relative positions. Thus the lock is effective to hold the indicating means and shell 16 against unintentional displacement and concurrently to very securely lock the shaft S at the position to which it has been adjusted.

Since a fairly strong turning effort is required to be exerted on key 46 to effect spreading of the limbs of lock 48, there is substantially no chance of the lock being accidentally or unintentionally unlocked, a distinct advantage and improvement over prior art devices in which a strong force must be applied to effect setting of a locking device which then may with only a relatively slight accidentally-applied force be returned to unlocking attitude. Further, since the lock utilizes a space that is next-adjacent the panel P and encircling the potentiometer bushing B and nut N, it does not encroach upon space normally occupied by a technician in manually rotating the adjusting shaft by means of a knob. And since the indicator means utilizes only normally wasted space Within the exterior bounds of a knob, and furnishes a single, direct, and easily-readable numerical indication of the extent to which the shaft S has been adjusted, all likelihood of incorrectly arriving at the adjustment value as indicated by two or more scale devices is obviated; and correct reading of indications is made extremely easy and simple.

A modified form of lock component is illustrated in FIGURE 7, wherein the elements previously described are the same excepting only lock 148 which in the modified form is a coil of two or more turns of strong spring wire with one or more small intermediate loops encircling anchor 12a and with upturned ends or tip portions 148a and 148k arranged to be spread by theblade 46b of key 46. Brake 148 is strongly contractile whereby it grips and locks drum 42d and facing 50 until it is forcibly expanded by forcible rotation of key 46. In other respects the assembly operates as previously described.

The preceding description of a presently preferred physical embodiment of the invention makes it evident that the aforementioned objects have been fully achieved. In the light of the disclosure various changes an-d modifications within the true spirit and scope of the invention will occurto others; and accordingly we do not wish the inventionto be restricted to exact details of the described structure except as is required by the appended claims.

' We claim:

'1. A variable resistor indicating and lock device adapted for attachment as a unit to a rotary variable resistor adjustment shaft extending through a panel to which such resistor is affixed, said device comprising:

relatively stationary means including base means arranged to abut against a panel, and said stationary means including a hollow support means secured to and extending forwardly of said base means;

relatively rotatable means, including a rotary transmitter mounted in said stationary means between said base means and said support means to be secured to such adjustment shaft, said rotatable means including a rotary shell shape to be grasped and rotated by hand, said shell being rotatably supported on said support means; indicator means supported by and mounted on said relatively stationary means and including a series of counter wheels each bearing numerical indicia, said indicator means being enclosed in said rotary shell and presenting an aligned series of numercial indicia;

lock means including an expandable contractile spring device having oppositely curved limbs embracing said transmitter and effective to lock said transmitter against rotation, said stationary means including means anchoring said spring device to said relatively stationary means and said lock means comprising key means for spreading the limbs of said spring device to release said transmitter; and

gearing means mounted on said stationary means and interconnecting said rotary shell, said indicator means and said transmitter;

whereby when said transmitter is secured to the shaft and said key means is operated to spread said spring device, rotation of said shell causes rotation of said gearing and effects concurrent rotation of the shaft and the indicator means to indicate the extent of adjustment of said shaft, and whereby thereafter further operation of said key means releases said contractile spring device and said shaft, shell and indicator means are thereby locked againstrelative displacement. a t

2. A device according to claim 1, in which said rotary shell comprises integral therewith a ring gear whicht-serves as a driving gear among said gearing means,-foroperat ing said indicator means and-saidtransmittenx 3. A device according to claim-1, in which said ge ring means comprises a first pinion connected tozsaid-indicator means for operating the latter, an idler pinion meshed with said first pinion, a ring gear on said shell engaging said firstpinion to drive the latter, and ,a ring gear on said transmitter in mesh with said idler pinion, whereby until said key means is operated to spread said spring device, said transmitter is effective through said gearing means to prevent unintentional displacement of said. indicator means and said rotary shell.

4. A device according to claim 1, in which said indicator means is enclosed within said rotary shell and said shell comprises a transparent face through which indicia on said counter wheels are visible, and in which said stationary means comprises an end cap having a window restricting the visible portions of said wheels to asingle aligned series of indicia thereon.

5. A device according to claim-1, in which said base means comprises means for supporting said key means ad jacent the rear face thereof and outwardly of the region of operation of said rotary shell, whereby said key means may easily be operated without likelihood .of unintentional displacement of said rotary shell.

6. A device according to claim 1, including means for restricting rotational displacement of said indicating and locking device about the axis of a shaft to which said device is attached.

References Cited UNITED STATES PATENTS 694,393 3/1902 Larson 188-77 2,539,575 1/1951 George 116-133 2,777,637 1/1957 Matthew 235-103 2,805,636 9/1957 Smith 116-115 2,901,998 9/1959 Keith 116-115 2,979,258 4/1961 Van Allen '235-103 3,031,035 4/1962 Tomita 188-71 3,183,885 5/1965 Venema 235-103 XR 3,202,127 8/ 1965 Struble et al 116-115 LOUIS I. CAPOZI, Primary Examiner. 

